1. Field of the Invention
The present invention relates to an improvement of a camera incorporating both of an auto-focus function and an auto-zoom function.
2. Related Background Art
In recent years, an auto-focus detecting device of the camera has involved the wide use of a focus detecting system. This focus detecting device detects a defocus quantity of an object by obtaining a relative position shift quantity of a pair of image signals obtained with a photoelectric conversion of an object image by imaging, on a couple of line sensors, beams of light coming from an object and passing through different exit pupil areas (focus detection areas) of a photographing lens. Known also is a camera in which a plurality of focus detecting systems described above are disposed to make the focus detectable in a plurality of areas.
In the cameras including the plurality of focus detecting systems, there is also known a camera of such a type that an element for selecting a focus detecting area to be focused from the plurality of focus detecting systems automatically selects this focus detection area in accordance with a fixed algorithm.
Apart from this, there is also known an auto-zoom camera in which the photographing lens serves as a zoom optical system, a zoom driving element thereof is provided, and the camera automatically adjusts a view angle except when a manual zoom operation is selected by the photographer.
For matching the automation technology such as the above-mentioned auto-focus and auto-zoom to intentions of the photographer, there is also proposed a line-of-sight detection technique of detecting where the photographer gazes in a finder, i.e., in a photographing picture.
Note that, for example, Japanese Patent Laid-Open Application Nos. 1-288812 and 1-288813 by the present applicant disclose the cameras each having the plurality of focus detection systems, wherein the camera automatically selects the focus detection area to be focused from the plurality of focus detection systems in accordance with the fixed algorithm. In addition, Japanese Patent Application Laid-Open No. 1-241511 by the present applicant discloses a technique including a line-of-sight detecting element applied to the camera automation technology.
In the camera incorporating the automation technology like the above auto-focus and auto-zoom as constructive requirements, the usefulness to the photographer depends largely on when to make the auto-focus and auto-zoom functions operative. The cameras which have hitherto been proposed, however, present the following problems.
1) In the camera of such a type that the auto-focus and auto-zoom functions work in interlock with manipulations of a release switch of the camera, an in-focus condition is not yet obtained just when holding the camera before manipulating the release switch. A focal length is also in an arbitrary position, and, therefore, the object can not be caught even by viewing through the finder in many cases.
2) As an improved version of the camera of the type 1), there is proposed a camera constructed to cause the auto-focus and auto-zoom functions to work by detecting that the photographer holds the camera and views through the finder. In this type of camera, the element for effecting the detection of viewing through the finder simply detects that the object approaches an eyepiece. Hence, the auto-focus and auto-zoom functions work also when something other than an eye of the photographer approaches the eyepiece. Only detecting that the object approaches the eyepiece does not imply detecting that the photographer holds the camera and certainly comes into a ready-for-photographing posture. There exists a great possibility to cause the auto-focus and auto-zoom functions to work in the middle of coming into the ready-for-photographing posture.
3) In the camera of the type 2), a timing for causing the auto-focus and auto-zoom functions to work is restricted to first one time when the photographer actually holds the camera. It is therefore impossible to correspond to variations in terms of photographing conditions concomitant to a passage of time thereafter.